libstdc++: Fix Doxygen markup error

	* include/bits/stl_pair.h (pair): Remove stray Doxygen closing marker.

From-SVN: r278950

libstdc++-v3/ChangeLog

 2019-12-03  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/stl_pair.h (pair): Remove stray Doxygen closing marker.
+
 	* testsuite/util/slow_clock.h: Fix copyright date.
 
 2019-12-02  Mike Crowe  <mac@mcrowe.com>

libstdc++-v3/include/bits/stl_pair.h

@@ -272,7 +272,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       explicit constexpr pair(const _T1& __a, const _T2& __b)
       : first(__a), second(__b) { }
 #endif
-      //@}
 
 #if __cplusplus < 201103L
       /// There is also a templated constructor to convert from other pairs.